1. Field Of Invention
The present invention relates to presses, and is more particularly concerned with a press of the type comprising means for clamping together the member of a die set having members mounted therebetween for such processes as the molding of plastics or metals, blanking, stamping and piercing.
2. Prior Art
Molding machines for molding plastics or metals as well as machines for blanking, stamping and piercing are well known in the art. Such presses generally include a stationary plate or bolster mounted on a base and a movable plate mounted for up-and-down or lateral movement with respect to the stationary plate. Die sets are generally utilized in which one member is affixed to the lower bolster and the other member to the upper bolster. Complementary mold members are generally mounted on the die set plates. The upper bolster is generally powered by either a hydraulic cylinder or a toggle assembly causing it to clamp the die set against the lower bolster under high pressure. Such types of apparatus have many disadvantages. First, it is dangerous for the operator to reach between the bolsters with his hands to load the moldable material and remove the finished molded products, since the bolsters may be accidentally actuated with resulting injury to the operator. Moreover, it is difficult and time consuming to perform such an operation. Additionally, it is difficult to change dies when they are permanently mounted on the bolsters. Molding machines have been disclosed in which the lower bolster and lower die plate are moved out of the molding position for unloading, but in doing so the upper die plate must be moved off the leader pins with resultant danger of their destruction.